Ultrasound Ovarian-Adnexal Reporting and Data System (O-RADS) and modified ultrasound simple rules comparison in evaluation of surgically proven adnexal masses

AIM: The aim of this study was validating Ovarian-Adnexal Reporting and Data System (O-RADS) 2022 risk estimates in surgically treated ovarian/adnexal masses comparing accuracy of O-RADS with modified ultrasound simple rules (mUSR) differentiating malignant from benign lesions. The mUSR was a simplified version of the International Ovarian Tumor Analysis (IOTA) using a binary classification of adnexal masses into benign/suspicious for malignancy. MATERIALS AND METHODS: multisite retrospective study was conducted including patients with pathology-proven adnexal masses between January 2008 and December 2018. All ultrasound (US) video clips reviewed by an experienced radiologist with randomly selected subset were reviewed by two additional radiologists. Areas under receiver operator characteristic curves (AUCs) were compared without and with CA-125. RESULTS: 791 ovarian masses in 765 patients (26 bilateral) (mean age: 44 ± 15 years) (628 benign, 49 borderline, and 114 malignancies) demonstrated malignancy rates of 0.3%, 3.0%, 24.9%, and 82.4% for O-RADS 2, 3, 4, and 5, respectively. O-RADS and mUSR had a sensitivity of 0.96 (confidence interval [CI]: 0.92-0.99) and 0.96 (CI: 0.91-0.98), negative predictive values (NPVs) of 0.99 (CI: 0.97-1.00) and 0.99 (CI: 0.98-1.00) (P>0.05), specificities 0.75 [CI: 0.71-0.78] and 0.88 [CI: 0.85-0.91], and positive predictive values (PPVs) 0.50 (CI: 0.44-0.55) and 0.68 (CI: 0.61-0.74) (P<0.01), respectively. The AUC was 0.855 for O-RADS and 0.920 for mUSR (P=0.005). Interobserver agreement was excellent across all readers for mUSR benign versus mUSR malignant and O-RADS 2/3 versus O-RADS 4/5 (kappa > 0.86). CA 125 improved performance of mUSR (P=0.002) and O-RADS (P=0.005) only in perimenopausal/postmenopausal patients. CONCLUSION: O-RADS and mUSR both with high sensitivity and NPV for detection of ovarian malignancy but mUSR with significantly higher specificity and PPV than O-RADS. This finding endorses the American College of Radiology (ACR) recommendation for expert sonologist consultation for O-RADS 3 and 4.